Steam humidifying device,especially for paper webs



G. MULLER June 10, I969 STEAM HUMIDIFYING DEVICE, ESPECIALLY FOR PAPER WEBS Filed May 9, 1966 United States Patent 3,448,484 STEAM HUMIDIFYING DEVICE, ESPECIALLY FOR PAPER WEBS Gernot Miiller, Krefeld, Germany, assignor to Job. Kleinewefers Sohne, Krefeld, Germany Filed May 9, 1966, Ser. No. 548,778 Claims priority, application Ggrmany, May 10, 1965,

K Int. Cl. Bti8b 3/00 10 Claims U.S. Cl. 306

The present invention relates to a device for steam humidifying fiat goods, especially webs of paper, as is customary when satining or glazing papers by means of calendars.

In order to obtain a uniform humidification, the employment of saturated steam has been preferred even though considerable drawbacks have been encountered. These drawbacks consist primarily in that the steam released from a nozzle pipe arranged in the immediate vicinity of the paper passing by does not completely condense on the cold paper but remains free to a considerable extent and enters the processing shop whereby mist and vapors form in the machine shop and condense on the cold machine parts of the calendar and adjacent machines.

In order to obviate this drawback, recently the old procedure has again been adopted to spray with cold water. To this end, for purposes of obtaining the desired uniformity of the water spray, the water is sprayed by means of high speed brushes or by means of spray nozzles.

However, also this method has not yielded the desired success because also the smallest water droplets are still greater than the pores of the goods so that the humidity cannot penetrate deeply enough and is retained in the upper fiber layer which swells first. In an effort to overcome this situation, it has been suggested to pass the goods over a plane or cylindrical suction surface under a vacuum and to carry out the spraying action within this area. It was expected that the humidity would penetrate deeper into the goods in view of the capillaries under subatmospheric pressure. However, experience has shown that this device has not proved satisfatory aside from the relatively expensive technical devices employed. At the high operating speeds of modern calendars up to 800 meters per minute, the said suction eifect causes considerable frictional forces between the paper and the suction chamber. As a result thereof, not only will the paper he overheated, but the increased amount of rubbed off material clogs up the pores of the suction chamber within a short time so that the vacuum of said suction chamber can no longer act upon the paper web. Furthermore, the elfect of this device is greatly dependent on the greatly varying air permeability of the different paper qualities. The surface humidification during the satining or glazing operation is of particular importance for coated papers which, however, are air non-permeable to a great extent.

It is, therefore, an object of the present invention to provide a device for steam humidifying flat goods, especially webs of paper, which will overcome the above mentioned drawbacks.

It is another object of this invention to provide a device for steam humidifying flat goods, especially Webs of paper, which will assure that the steam will deeply penetrate into the capillaries of the paper web being passed by the device.

It is still another object of this invention to provide a device as set forth in the preceding paragraphs, which in addition to a good humidification of the web material passing by said device will also reduce the friction between the web material and the device being passed over by the web material.

These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawing diagrammatically illustrating a device according to the present invention in connection with a calender.

The above mentioned objects have been realized according to the present invention by passing the web material over a hollow direction reversing beam which acts in the manner of a reversing roller and is provided with a curved surface. Humidifying steam is introduced into the said hollow beam and passes through steam releasing nozzles in said beam against the web material while said nozzles are arranged along that curved outer surface of said beam against which the web material is being pressed at the highest pressure or just past the area where the pressure at which the web material is being pressed against the surface of said beam just begins to decrease. In view of the strong engagement of the beam surface by the paper web within the area of the steam nozzles, the steam is prevented from escaping into the machine shop and is forced to penetrate under a certain overpressure deeply into the capillaries of the web material passing over said surface area. At the same time, the friction between the web material and the surface area of said beam is reduced because the steam leaving the nozzles and acting upon the adjacent surface of the web material creates a certain cushion. This brings about the particular advantage that the wet steam which is under pressure is in view of the roughness existing in the microrange of the web material carried along by the latter and forms a steam film carrying the web material. This steam film due to its overpressure brings about an intensive contact between the fibers of the web material and the steam. This in turn brings about that due to the temperature drop with in the layer of the web material, the steam condensates and deeply penetrates into the fibers of the web material while the steam becomes less and less toward the end of the path around said beam.

The temperature drop may be controlled according to the present invention by a variable cooling of the web material. Such control may be arranged along that area of the beam where the web material again leaves said beam. The cooling device may be arranged on the inside and/ or the outside of the beam.

According to a further development of the present invention, the curvature of the beam surface over which the web material passes is so selected that the upper surface area over which the web material passes first has a radius of curvature which is considerably shorter than the radius of curvature of that area where the web material again leaves the beam. The steam nozzles are arranged within the surface area with the shorter radius of curvature, i.e. within the area which is considerably more curved than the area where the web material leaves the beam. As a result thereof, within the area of the nozzles, the web material is pressed against the beam under con- J siderable pressure whereas the friction between the web material and the area where the Web material leaves said beam is considerably reduced.

The uniform steam distribution within the direction reversing beam is effected in a manner known per se, for instance by two pipes arranged one within the other. The steam enters the inner pipe of smaller diameter and through nozzles distributes itself in the outer pipe from where it passes-through additional nozzles arranged on that side which is opposite to the side Where the first noz zles are located and passes into the inner chamber of said beam from where it flows to the humidifying nozzles. The entire arrangement may be so designed that the outer steam pipe forms the supporting body for the entire beam which advantageously is made of sheet metal.

According to a still further development of the present invention, the direction reversing beam is rotated about the axis of the steam feeding pipe which is eccentrically located within said beam. By rotating the beam about the axis of said steam feeding pipe, it is possible to adapt the tension within the two areas of curvature of the beam to the respective quality of the' web material, such as paper. Another advantage of the direction reversing beam is also seen in the fact that it can take the place of the direction reversing rollers which are customarily arranged on the second steel roller of paper satining calendars. At the same time, by providing corresponding adjusting means and a spherical curvature, the beam according to the present invention can take over the function of such rollers for maintaining the straight course of the webs and for holding the webs spread out.

Referring now to the drawing in detail, the direction reversing beam 1 according to the present invention is shown arranged within the area of the second steel roller 2 of a calender which steel roller is located between two elastic rollers 3. The direction reversing beam 1 of the present invention forms in this arrangement the direction reversing means associated with roller 2. As will be seen from the drawing, the paper web 4 leaves the upper bite between steel roller 2 and elastic roller 3 and moves in the direction of the arrow A over the curved outer surface of beam 1 and in the direction of the arrow B returns into the lower bite between steel roller 2 and elastic roller 3a. The curved surface of beam 1 over which the web material passes is formed by a curved steel metal sheet 5. As is evident from the drawing, the upper beam surface area is curved to a considerably greater extent than the lower beam surface area. Within the area of the upper curvature there is provided a narrow steam release slot or a row of nozzles 7 for the release of humidifying steam. In view of the sharper curvature, the paper web passing thereover will be pressed against the metal sheet 5 at a considerably greater pressure than is the case at the lower surface area of beam 1 which is considerably less curved. Therefore, the row of nozzles 7 .is arranged within the range of the greatest pressure or still better shortly therebehind when looking in the direction of movement of the paper web over the beam so that the steam leaving the nozzles will have the possibility to pass in a certain quantity below the paper web and to produce the deep penetrating effect outlined further above. Metal sheet 5 is by means of a strip 6 welded to a pipe 8 of relatively large diameter so that a hollow chamber 9 is formed in which the steam can spread.

The supply of steam is effected in a manner known per se -by a small pipe 10 which is arranged in pipe 8 in spaced relationship thereto. Pipe 10 is connected to a steam supply line 11 and is rotatably journalled in bearings 12. The inner steam pipe 10 has upwardly directed nozzles 13, whereas the nozzles 14 of the outer steam pipe are directed downwardly. This arrangement will assure a uniform distribution of the steam within beam 1 and will also assure a trouble-free release of the condensate through a conduit 15 for the evaporated liquid.

In order to obtain an intensive deposit of the humidity upon the paper, the temperature drop may be controlled by a cooling device. This may be effected by an insulating layer 16 provided in the interior of the lower portion of beam 1 and/ or by an air nozzle pipe 17 arranged outside said beam 1. Pipe 17 is provided with nozzles 18 through which cooling air is blown onto the web material.

In order to prevent the release of steam from those nozzles 7 which, when the width of the web material does not cover these nozzles, are free, according to a further development of the present invention, dovetailed sliding members 20 are arranged in profiled rails 19 within the direction reversing beam 1 for closing the marginal nozzles over the necessary width of the beam. The tilting of the beam 1 may be effected in any desired manner, for instance through the intervention of adjustable linkage means 21.

It is, of course, to be understood that the present invention is, by no means, limited to the particular arrangement shown in the drawing but also comprises any modifications within the scope of the appended claims.

What I claim is:

1. A device for steam humidifying flat goods, especially webs of paper, particularly for use in connection with calendars, which comprises: a hollow beam having a curved outer entrance surface area for receiving flat goods in a continuous movement from the respective upper portion of a rotatable roller and also including a releasing surface area for returning the goods passed over said entrance surface area to the respective lower portion of the same roller from which the goods are fed to said entrance area, and steam conveying means leading from the interior of said hollow beam to approximately that surface section of said entrance surface area which will be under the greatest looping pressure when the respective goods are looped around and passed over said curved outer surface of said beam.

2. A device according to claim 1, in which said curved outer surface also includes a curved intermediate surface area with the radius of curvature thereof gradually increasing from said entrance surface area to said releasing surface area, the radius of curvature of said entrance surface area being considerably less than that of said releasing area whereby the respective portions of the goods passing over said entrance area will be pressed thereagainst at a considerably higher pressure than the pressure holding the respective portions of the goods passing over said releasing area close to the latter.

3. A device according to claim 1, which includes insulating means arranged on the inside of that wall portion of said hollow beam which forms said releasing surface area.

4. A device according to claim 1, which includes air cooled jacket means arranged on the inside of that wall portion of said hollow beam which forms said releasing surface area.

5. A device according to claim 1, which includes nozzle pipe means adapted to be connected to a supply of cooling air and located within the range of said releasing surface area for directing cooling air onto flat goods passing over said releasing surface area.

6. A device according to claim 1, in which the outer surface of said hollow beam is curved in a direction transverse to the path of movement of the flat goods from said receiving area to said releasing area.

7. A device according to claim 1, which includes bearing means eccentrically pivotally supporting said hollow beam.

8. A device according to claim 1, in which said steam conveying means includes steam nozzle means extending from one marginal portion of said receiving area to the oppositely located marginal portion of said receiving area, and means associated with at least those nozzle means which are adjacent said marginal portions for selectively closing the same, whereby those nozzle means can be 5 made ineffective which are not covered by the flat goods passing thereover.

9. A device according to claim 8, which includes means associated with said steam nozzle means and'operable to control the steam pressure of the steam to be passed therethrough in conformity with the degree of humidity of the flat goods to be passed over said entrance area.

10. A device according to claim 1, in which said steam conveying means includes a plurality of co-axially arranged pipe means located one within the other and respectively provided with steam outlet means in alternate directions, at least some of said pipe means forming part of the frame work of said beam.

References Cited UNITED STATES PATENTS 2,304,474 12/1942 Poesl 15-306 XR 2,718,712 9/1955 Bruker et a1 15307 XR 2,974,512 3/ 1961 Carter 68--5 ROBERT L. BLEUTGE, Primary Examiner.

US. Cl. X.R. 

1. A DEVICE FOR STEAM HUMIDIFYING FLAT GOODS, ESPECIALLY WEBS OF PAPER, PARTICULARLY FOR USE IN CONNECTION WITH CALENDARS, WHICH COMPRISES: A HOLLOW BEAM HAVING A CURVED OUTER ENTRANCE SURFACE AREA FOR RECEIVING FLAT GOODS IN A CONTINUOUS MOVEMENT FROM THE RESPECTIVE UPPER PORTION OF A ROTATABLE ROLLER AND ALSO INCLUDING A RELEASING SURFACE AREA FOR RETURNING THE GOODS PASSED OVER SAID ENTRANCE SURFACE AREA TO THE RESPECTIVE LOWER PORTION OF THE SAME ROLLER FROM WHICH THE GOODS ARE FED TO SAID ENTRANCE AREA, AND STEAM CONVEYING MEANS LEADING FROM THE INTERIOR OF SAID HOLLOW BEAM TO APPROXIMATELY THAT SURFACE SECTION OF SAID ENTRANCE SURFACE AREA WHICH WILL BE UNDER THE GREATEST LOOPING PRESSURE WHEN THE RESPECTIVE GOODS ARE LOOPED AROUND AND PASSED OVER SAID CURVED OUTER SURFACE OF SAID BEAM. 